ROTARY DRAW BENDING

Rotary Draw Bending is a Quick Setup module in eta/DYNAFORM for performing rotary draw bending of tubular products. This is a process oriented module with user-friendly GUI. Furthermore, it provides functions to enable the user to easily generate tube and toolings of rotary draw bending models.

 

The Rotary Draw Bending interface is illustrated in Figure 8.1.12. The user can obtain the complete analysis model using the default parameters. The program requires the user to confirm the thickness of tube blank and define the tube blank first and then define tools (refer to the location and size of tube blank).

 

NOTE: Rotary bending simulation only supports global coordinate system and the rotation axis is +Z axis.

Figure 8.1.12  Quick Setup / Rotary Draw Bending GUI

 

The following options are included in the Rotary Draw Bending interface:

 

Auto Assign:  Assign the part with standard name as the corresponding tool, e.g. TUBE, BEND, CLAMP, INSERT, PRESS, WIPER, PUSH, MANDREL, BALL and LINK.

Advanced:  Modify the setting of default parameters of rotary draw bending.

Preview:  Check the motion of tool by animation.

Save:  Save the database without exiting the Rotary Draw Bending interface.

 

Help:  Provide useful information about simulation process.

Apply:  Activate the program to define tool motion curve, etc.

Reset:  Restore to the original setting.

Write Dyna:  Export LS-DYNA deck.

Submit Job:  Submit input deck to solver for analysis.

Exit:  Exit the Rotary Draw Bending interface.

 

8.1.4.1       TOOL DEFINITION GUI

This function allows the user to assign or create tools and tube blank mesh for rotary draw bending. After all the tools are defined, the outline of tools is displayed in green.

 

TUBE

The Define Tube dialog box is illustrated in Figure 8.1.13.

Figure 8.1.13  Define Tube dialog box

 

ADD PART

Select a part from the Select Part dialog as tube. The selected part will be displayed in the Part List.

 

REMOVE PART

Remove the selected part from the Part List.

 

COPY ELEM

Generate elements by duplicating the existing elements.

 

USER DEFINE

Generate tube geometry. The dialog box is illustrated in Figure 8.1.14.

Figure 8.1.14  Define Geometry dialog box

 

OUTER DIAMETER

Outer diameter of tube.

FULL_LENGTH

Length of tube.

BEND_LENGTH

Bend length of tube.

DIVISIONS

Number of mesh divisions along tube parameter.

LOCATION

Define the starting location of tube blank bending, which also locates on the tube blank axis.

DIRECTION

Define the direction of tube centerline.

REVERSE

Reverse direction of bend length after generation of mesh.

FLIP

Reverse direction of bend length prior to generation of mesh.

Figure 8.1.15  Tube Blank Geometry

 

APPLY: Generate mesh according to the specified parameters.

UNDO: Cancel the operation of generating mesh.

CLOSE: Exit the current dialog box.

 

TOOL TRANSFORMATION

This function allows the user to translate and/or rotate the defined tube.

       

Figure 8.1.16  Transformation dialog box

 

X-AXIS

Translate or rotate along (about) X axis.

Y-AXIS

Translate or rotate along (about) Y axis.

Z-AXIS

Translate or rotate along (about) Z axis.

TWO POINTS

Translate or rotate along (about) the vector direction defined by two points.

DISTANCE

Translation distance.

ANGLE

Rotation angle.

 

REVERSE:  Translate or rotate along (about) the reverse direction.

APPLY:         Execute translation or rotation.

EXIT:            Exit the current dialog box.

 

DISPLAY

This function allows the user to only display the current defined object on the screen. Click on this button again to display the other objects.

 

EXIT

Exit the current dialog box.

 

BEND DIE

The definition of BEND DIE is similar to definition of tube. As shown in Figure 8.1.17, the user can generate geometry of BEND DIE by defining the bend die diameter (D) and radius (R) illustrated in Figure 8.1.18.

Figure 8.1.17  Define Geometry

Figure 8.1.18  Parameters defining geometry of Bend Die

 

MANDREL ASSEMBLY

The mandrel Assembly Definition dialog box is illustrated in Figure 8.1.19. A typical mandrel assembly consists of mandrel shaft, balls and links between balls. The user can generate the mandrel assembly by entering the related dimensions. After defining the mandrel shaft and balls, links are automatically generated and connects the mandrel shaft and balls. The user can click on the Advanced button to define desired contact type and parameters, as shown in Figure 8.1.20.

Figure 8.1.19  Mandrel Assembly Definition

Figure 8.1.20  Contact dialog box

Figure 8.1.21  Defined Mandrel Assembly

After the mandrel assembly is defined, an interface as illustrated in Figure 8.1.21 is displayed. In the Link field, the user can click on Check or Modify Constrained button to check of the definition of constraints. In the Joints field, the user can click on Define button to modify the NID of connected nodes. The coupled nodes indicate the connection between links.

 

As shown in Figure 8.1.22, the tool font color and background color are displayed with the color of tool mesh. The user can click on the buttons in the dialog window to edit the relationship of constraint.

 

Figure 8.1.22  Constrained Parts

 

CLAMP DIE

The Define Geometry dialog box for CLAMP DIE is illustrated in Figure 8.1.23.

Figure 8.1.23  Define Geometry

Figure 8.1.24  Parameters defining geometry of Clamp Die

The definition of other tools are similar to the one described above. Usually, the user adopts the default base point without assigning one for the user-defined tool. The user must check the correctness of direction when generating tool mesh.

 

8.1.4.2       TUBE PARAMETERS

Tube Parameters includes MATERIAL, THICKNESS, PROPERTY and CONTACT types and parameters.

 

MATERIAL

Refer to Section 11.9  for description about tube material definition.

 

THICKNESS

The user must define the tube wall thickness prior to defining the tube geometry. By default, the thickness is set as 2.0 (mm).

 

PROPERTY

Property includes selection of element formulation, number of integration points and the setting of shear correction factor.

 

8.1.4.3       BEND DIE CENTER

The center of bend die defines the center of rotation for rotary draw bending. If the bend die is created by the program, the center of rotation is identical to the geometry center. After the bend die is defined, the coordinate of rotation center is displayed. The user can click on USER DEFINE… button to define new rotation center. The user may click on the RESET CENTER button to restore the original rotation center.

 

8.1.4.4       TOOL CONTROL

Tool control field enables the user to define the velocity and rotation angle of bend die, as well as the motion of push assist. The motion of push assist can be defined using one of the 3 options: AUTOMATIC, VELOCITY and DISPLCMNT. If AUTOMATIC option is chosen, the velocity curve is automatically assigned according to the pre-defined velocity. For VELOCITY and DISPLCEMNT option, click on DEFINE… button to define the velocity or displacement curve. Refer to Section 8.2.4.2  for description about curve definition.

 

8.1.4.5       GENERAL

This function allows the user to set the Tool Acceleration Time and output Frame number. The default acceleration time is set as 0.002(s), while the default output frame number is set as15.